Veterinary Histology

Reviewed by Jenny Maldonado, Assistant Professor of Biology, University of Saint Francis on 12/31/21

Comprehensiveness rating: 5 see less

The text is quite comprehensive, it covers the anatomical systems of vertebrates from the cell to special senses.

Content Accuracy rating: 5

I found no errors in the book.

Relevance/Longevity rating: 5

Histology doesn't really change with respect to up-to-date context. Having said that, this text is written in a way that should stand the test of time.

Clarity rating: 5

The book uses clear, concise vocabulary. I like the use of keywords and the overview to know at the beginning of each chapter that helps the reader understand the important concepts that will be learned throughout the chapter.

Consistency rating: 5

There were several times in several chapters where concepts or vocabulary words were used again and again in identifying features in the histology, I think if students notice that, it should be a great learning tool for them.

Modularity rating: 5

I really liked the breakdown of the chapters, it made reading the textbook quite enjoyable. And I could go back to keywords if I needed to. I really like the arrows at the bottom of the pages that quickly allowed me to go to the next page quickly.

Organization/Structure/Flow rating: 5

The organization of the book was very good, and is consistent with other Anatomy and Physiology books.

Interface rating: 5

I thought the text was very easy to learn and understand. I especially like the histology slide photos in the middle of the pages with headings and labels. I often enlarged the photos to full page, and the images did not get distorted.

Grammatical Errors rating: 5

I didn't find any grammatical errors.

Cultural Relevance rating: 5

I found nothing offensive in the text.

Comments

This e-book would be a great supplemental lab book to an undergraduate comparative anatomy and physiology lecture or lab. I found it to be very concise, and informative, with really great photomicrographs of the histology. The photomicrographs are very well labeled, often interactive and have good information displayed on the side of them that describe the histology.

Reviewed by Douglas Baird, Associate Professor, Neurobiology & Anatomy, Director of Curricular Innovation & Student Success, Drexel University College of Medicine on 5/28/19

Comprehensiveness rating: 1 see less

The goal of proving an open textbook in veterinary histology is a worthy one. The present effort falls far short of the quality found in most histology textbooks. Major organ systems are not included: endocrine organs like adrenal, pituitary and thyroid glands, and nervous tissues, even though nervous tissue are listed as one of the four, basic types of tissues. The major shortcoming of this text is the paucity of figures and diagrams. As an anatomical science, histology is a visual subject. The material is best understood via illustration. The figures that appear lack captions and rarely have annotation directing the reader to structures mentioned in the text.
There are no figures in this text that compare two species, for example, and in some of the sections that I reviewed, species-specific differences are not addressed. When the authors describe, but never illustrate, species differences, the authors focus exclusively on mammals, with no mention of of non-mammalian classes, including birds and reptiles that represent a significant portion of the animals treated in some practices. Even among mammals there is variation relevant to veterinarians, variation that is not illustrated (e.g. in "Male Reproductive System Chapter), and sometimes not even mentioned (e.g. variation in kidney and other structures is not mentioned in Urinary System chapter).

Appendix one includes helpful illustrations of the process of preparing, staining and mounting histological sections. Appendix 2 is woefully incomplete, dealing only with "H&E" staining, and completely omitting mention of other staining and preparation methods that the veterinary student is likely to encounter in their studies of pathology and in clinical practice. Appendix 3 is helpful, but should mention that red blood cells are often a handy yardstick, and discuss any species-specific variation in cell type sizes.

Content Accuracy rating: 2

The text includes a number of errors. The lack of rigor in language usage could easily lead to misconceptions among students of histology. In the four chapters that I reviewed, one figure had errors, including an unintentionally duplicated image, and another had incorrect annotations. Please see "other comments" at the end of this review for many examples of errors and lack of rigor in language.

Relevance/Longevity rating: 4

Histology does not change rapidly. The text includes up-to-date material in cell biology, which changes more rapidly, and which can be easily updated as need be.

Clarity rating: 3

While the prose is clear, the descriptions are sometimes incomplete, overly broad and could lead to misconceptions. See "other comments" at the bottom of this review for examples.

Consistency rating: 5

The authors consistently employ a well-designed structure.

Modularity rating: 4

The materials is "well chunked" into sections that can be quickly mastered--although this process goes too far in some sections that only consist of a single, short paragraph, with no illustrations.

Organization/Structure/Flow rating: 3

The authors include a list of learning objectives at the start of every chapter, a feature that many readers will find helpful. The glossaries at the start of each chapter are also useful in principle, although some of the explanatory material is over-simplified, or overly-broad, especially in a text directed at high-performing graduate students, and could lead to misconceptions.

Interface rating: 3

Figures often include multiple, "stacked" images, which makes them compact, but because they are stacked, only one image can be viewed at time. This format has pedagogical limitations: direct comparisons between figures are difficult, without opening the text and figure in multiple windows. Also all the images in one section are present in a single stack, and the stack is open not visible when reading the text that corresponds to one or more of the images in the stack.

Grammatical Errors rating: 2

Grammatical and typographical errors were common, indicating that this text has not been carefully edited. See "other comments" below for specific examples of errors found in the four chapters reviewed.

Cultural Relevance rating: 5

The four chapters I reviewed did not include any insensitive or offensive text. I don't know that racial/ethnic/background inclusiveness is relevant to selecting histological examples.

Comments

My qualifications as a reviewer: 27 years teaching histology to medical, pre-medical graduate and undergraduate students. Extensive familiarity with available histology educational resources, both traditional texts and open, online materials.

The goal of proving an open textbook in veterinary histology is a worthy one, given the cost of a veterinary degree, acknowledged by the authors. The present effort, however, falls far short of the quality found in most histology textbooks. The major shortcoming of this text is the paucity of figures and diagrams. As an anatomical science, histology is a visual subject. The material is best understood via illustration. The figures that appear often lack captions and rarely have annotation directing the reader to structures mentioned in the text. In one of the chapters that I reviewed, Male Reproductive System, one figure had errors, including an unintentionally duplicated image, and misleading annotations.

Grammatical and typographical errors were common, suggesting that this text has not been carefully edited.

There are no figures in this text that compare two species, for example, and in some of the sections that I reviewed, species-specific differences are not addressed. When the authors describe, but never illustrate, species differences, the authors focuses exclusively on mammals, with no mention of of non-mammalian classes, including birds and reptiles that represent a significant portion of the animals treated in some practices, and which are not as well represented in other texts.

Major organ systems are not included: endocrine organs like adrenal, pituitary and thyroid glands, and nervous tissues, even though nervous tissue are listed as one of the four, basic types of tissues.

The materials is "well chunked" into sections that can be quickly mastered--although this process goes to far in some sections that only consist of a single, short paragraph, with no illustrations.

Figures often include multiple, "stacked" images, which makes them compact, but because they are stacked, only one image can be viewed at time. This format has pedagogical limitations: direct comparisons between figures are difficult, without opening the text and figure in multiple windows. Also all the images in one section are present in a single stack, and the stack is open not visible when reading the text that corresponds to one or more of the images in the stack.
The authors include objectives and questions students should be able to answer at the start of each chapter, which is a positive, but the explanations in this keyword list re sometimes oversimplified, e.g. " Endoplasmic Reticulum
The organelle that is responsible for the synthesis of proteins (rough ER) or the synthesis of steroid hormones and detoxification
of certain agents (smooth ER)"
Couldn't a "ribosome" be defined in the same way as the authors defined one of the functions of "rough ER?"
Golgi Apparatus
The organelle that is responsible for protein packaging and processing.
Will students who have not studies cell biology know what is meant by "Packaging" in this context?

Intermediate Filaments
A broad class of cytoskeletal elements that provide structure and function to a cell.
Don't all organelles provide "function?" Like many of these definitions, it's too broad.

Meiosis
A specialized process of cell division that results in the formation of cells with half the chromosome number of the original cell.
Should say that these half chromosome cells are sperm and ova for reproduction--gametes
Microfilaments
Thin cytoskeletal elements that are predominantly involved in the movement of cellular elements. Elaborate--...elements important for cell shape and motility.
Microtubules
The component of the cytoskeleton that is composed of an α and β heterodimer of tubulin.
But microtubles are also involved in the movement of organelles attached to motor proteins. Better to say microtubles subserve both structural and organelle transport functions.

Perioxisomes
An organelle that breaks down H2O2 and excess fatty acids and is involved in cholesterol biosynthesis
Would asking for subscripts be too much?

In sum, the chapters that I reviewed, The Cell, Epithelium, Bone (which might be better titled "Skeletal Tissues, as it also includes Cartilage), and Male Reproductive System, were well below the standards of existing histology texts, both medical and veterinary. Most veterinary students would feel severely short-changed by the lack of effective illustrations in this text, and other shortcomings. I recommend that this text be removed from the Open Textbook Library, as I cannot recommend it, or individual chapters as supplements to other materials. Once the authors address these shortcomings, then the book might be re-evaluated for inclusion in the Library.

Below I list some of the specific issues and errors in the four chapters I reviewed. I hope the authors are working on a new edition and choose to address these:

I was appalled by the lack of diagrams and micrographs in Chapter 1 the cell. Histology is in essence a visual science--students should be able to recognize subcellular structures in EMs. Not just for the sake of doing so, but to better understand the relationships between subcellular structures. A major challenge for new students of histology is one of scale--in a micrograph, what are the nuclei, what are the cells, and what are multicellular structures? By not showing images of cells with some scale information, the authors are wasting an opportunity to help students with this challenge, to say nothing about giving the student an understanding of what organelles look like in electron micrographs, their relative sizes and locations in the cell.

From "The Cell Membrane":

"Other functions of the membrane are to subdivide the cytoplasm within the cell and increase surface area of the cell."

At the start of this sections, the authors describe what is often called the "plasma" membrane. Later, as above, the authors refer to "the membrane," and sound like they are using "cell membrane" and the bilayer membranes that surround organelles interchangeably. This sloppy use of terminology will be particularly confusing to the new students of cell biology and histology.

In "Nucleus and Nuclear Structures" section, the terms "eukaryote" and "prokaryote" are not defined. They should be defined here or in the keyword sections, where they are absent.

Terminology is introduced with no background or context. It will open be just so many new words for the beginner. For example: "However, a nuclear localization sequence is necessary before transport can occur. The fibrous lamina is the third component of the nuclear envelope. The fibrous lamina is composed of lamin and membrane-associated proteins and is found on the inner surface of the inner nuclear envelope."

Will students know that the authors are referring to the sequence of amino acid sequence of a protein when they refer to a nuclear localization sequence?

Similarly will students understand the significance of "hematoxylin and eosin staining" when it used in this section with no prior reference?
" Heterochromatin appears more basophilic than euchromatin with standard hematoxylin and eosin staining." Such a key procedure should be defined before it is used in the context of subcellular structure.

Rough ER is covered before ribosomes. Ribosomes should come first.

In the Golgi section: "Second, the Golgi then condenses the proteins, packaging them into membrane bound secretion granules." The authors should introduce the term of "vesicles," a broader term that includes "membrane bound secretion granules."

"Degradation Organelles": authors should mention "proteasomes" as a key structure for protein digestion. While many would not consider proteasomes to be organelles, I argue that if ribosomes are discussed, the protease possesses structural complexity on the level of a ribosome. More importantly, proteasome play a key role in degradation and should be included, whether technically an organelle or not.

"Perioxisomes also are involved in the synthesis of bile acids and myelin lipids as well as the breakdown of excess purines to uric acid." "bile acids" and "myelin lipids" should be defined.
"Mitochondria" section: "Mitochondria have a complex structure related to their sophisticated function in the cell and is the primary organelle that produces energy (ATP) for the cell." ATP is not energy per se. More appropriate to write (stored in the form of a high-energy bond between phosphate groups of adenine tri phosphate, "ATP")

" The mitochondria is composed of an outer and an inner membrane. The outer membrane is composed of a 50:50 lipid:protein mixture, porins, and numerous enzymes." Mitochondria are composed of more than just membrane. Better to say "mitochondria have an outer and an inner membrane."

Grammatical/typographical errors: " Between the outer and inner membrane, and intermembrane space contains enzymes that are necessary for nucleoside phosphate exchange."

" Mitochondria acontain genetic material that is inherited from the mother and is found in the mitochondrial matrix as a circular double stranded molecule.

"The presence of DNA in mitochondria provides evidence for how mitochondria may have developed in the cell, a process called mitochondrial biogenesis." Better to say "evolved" than "developed"

"Cytoskeleton and Filaments" section: the authors mention the role for desmin in muscle contraction, yet fail to mention any role for actin in muscle contraction, even though actin and myosin are the two major contractile proteins of muscle.

Grammatical error: "it is composed of an α and β heterodimer of tubulin that align in rows called protofilaments." should read "... composed of α and β heterodimers.."

Cell Inclusions section:
Grammatical errors: " Glucose molecules are connected by α(1-4) linkages and branched off" should read "...branch off..".

The second are aggregates of small particles (β-particles) called rosettes (α-particle)." Should read "...( α-particles)."

Lipid inclusions are termed "spheres." Should also note that these are typically referred to as "droplets."

"Karyotype is the arrangement of chromosomes based on size and morphology and is dependent on centromere location. " Karyotype is simple the number and appearance of chromosomes. It does not include their "arrangement." Use of "arrangement" implies that karyotype also includes the location of chromosomes in the nucleus, which is not correct.

Chapter 2 Epithelium. Epithelium is listed as one of the "..four basic tissues", but, tissues are never defined in this book.

"All epithelial tissue rests on a basement membrane. The basement membrane acts as a substrate on which epithelium can attach to as well as grow and regenerate after injuries." But what is a basement membrane--what is its composition? What does it look like?

"Desmosomes
A cell modification that is responsible a cell to cell adhesion resistant to shearing forces to the epithelial layer."
Desmosomes are a type of "cell "junction," rather than a "cell modification, which typically refers to a specializations such as cilia or microvilli.

Uroepithelium is commonly referred to as "transitional epithelium;" "transitional epithelium" should be included in the key word list. Uroepithelium is used by some authors, but it's adoption is not widespread.

Pseudostratified
A type of columnar epithelium in which the nuclei are arranged in different levels in the cell layer.
Simple
An unilayered arrangement of epithelial cells.
Stratified
A multilayered arrangement of epithelial cells.
The key difference between pseudostratifed and stratified is not clear from these definitions. In pseudostratified, all cells make contact with the basal lamina, and nuclei are typically not arranged in distinct layers. In stratified epithelia, the apical layers do not extend down to the basal lamina, and nuclei are typically arranged in tight layers.

Add "Squamous" to the list of keywords.

Missing word: "2. The regulation and exchange of molecules between the underlying tissues another compartment"
Good opportunity to introduce endocrine vs exocrine here: "The secretion of endocrine hormones into the blood vascular system, and/or the exocrine secretion of sweat, mucus, enzymes, and other products that are delivered apically by ducts"
 "Hepatocytes comprise a majority of the hepatic parenchyma and are considered epithelial cells." Good to explain to reader why hepatocyles are considered epithelial.

Suggested edits: "All epithelial cells types share the following characteristics:
1. Close apposition of cells.
2. Free surface of epithelial cells is adjacent to the space.
3. Basal surface is adjacent to connective tissue.
4. Sheets of epithelial cells may be modified into tubes forming glands.
5. Absence of blood vessels within epithelial layer"
Remove "cells"; not all epithelial cells have all these characteristics.

Finally, some figures! Should have some earlier than this. Figure has both diagram and micrograph example with is a plus. Figures lack annotations (e.g. arrows) to note locations of structures listed in captions. Most images do not indicate species, which will be of interest to most readers of a veterinary histology text.
Suggested Edits: Define squamous here; first usage: "1. Simple squamous: this type is found in lining areas where passive diffusion of gases occur, such as walls of capillaries and alveoli of the lungs. Endothelium is the special term used for simple squamous epithelium that lines the inside surface of a vascular structure."
"Tissues that line the inside of the mouth, the esophagus and part of the rectum are composed of nonkeratinized stratified squamous epithelium. Other surfaces that separate body cavities from the outside environment are lined by simple squamous, columnar, or pseudostratified epithelial cells, cells that are often keratinized.

This explanation of microvilli is incomplete, because it does not indicate how, the increase in surface is accomplished--what is the shape of microvilli? What cytoskeletal elements do they contace? "Microvilli are cell surface modifications which increase surface area of a cell without significantly increasing the size of the cell. Microvilli are often seen in organs where the epithelium plays a primary role in the absorption of molecules."

"Tight junctions are include transmembrane proteins on adjacent cells fused on outer plasma membrane."

"Desmosomes attach to the microfilaments intermediate filaments of cytoskeleton made up of keratin protein." No, desmosomes attach to intermediate filaments. Keratins are intermediate filaments.

CHAPTER 5: BONE, CARTILAGE, AND JOINTS
Grammatical errors: Described the methods in which bone is formed.
"What does the term modeling mean in terms of bony tissue?
Grammar/style: "What does the term remodeling mean in term the context of boney tissue? Compare and contrast remodeling and modeling"

• What is the physis and the significance of this finding its presence in a histologic section?
• What are the three types of cartilage and what locations where can they be found?
"Modeling differs from remodeling as bone can directly begin forming or resorbing (not the same activation-resorption-formation sequence as outlined below)."

Figures in this chapter include arrows and labels indicating cell types referenced in captions.
Statements like this which reference micrographs in the absence of a corresponding image will frustrate many readers: " The arrangement of collagen fibers in bone can be visualized under a polarizing microscope. Where fibers are arranged into dense parallel arrays, the bone is referred to as ‘lamellar’.

"The osteoclastblast initially releases collagenases that resorb the non-mineralized lamina limitans."

Statements like this are crying out for illustrative diagrams, or even better, an animation: " An osteonal remodeling unit is constantly changing. The osteon has a central cavity shaped like an ice-cream cone with osteoclasts at the top leading edge (called the ‘cutting cone’). Further away from the top, the cavity left by the cutting cone becomes progressively filled by new bone deposited in concentric lamellae (giving the remodeling unit a coned appearance in longitudinal section).  There are progressively more centripetal lamellae as sections are further from the site of osteoclastic resorption. When osteoclastic activity ceases, the top of the remodeling unit becomes filled and becomes a mature secondary osteon."

No figure illustrating membranous ossification.

Figure 9 and 10 are identical. Figure 10 does not match the caption--there is no radiograph:
New image
"Figure 10: Bone. The process of endochondral ossification takes place in the physeal cartilage. This area can be viewed on a radiograph of a long bone of a young animal as a linear radiolucent area. After the zone of hypertrophy, the chondrocytes die and the chondroid matrix is replaced by mineralized matrix."

A diagram illustrating the multiple, complex steps of endochondral ossificiation will be extremely helpful to the reader, but is absent.

No image of elastic cartilage.

The section on tendons and joins only described synovial joints. Other types of joints that are not mentioned: cartilaginous and fibrous joints.

"Lining The synovium lines the innermost aspect of the joint capsule is lined by synovium."

Male Reproductive System

In the figure of seminiferous tubules, primary spermatocyes are misidentified. The arrows indiction primary and secondary spermatocytes actually point to early spermatids in various stages of development. The primary spermatocytes are the larger cells located between the spermatogonia and the early spermatids. Secondary spermatocyes undergo the second meiotic division very rapidly and are therefore rarely visible in micrographs.

A diagram and figures that include each of these terms would greatly help the reader in several sections:
" The mature spermatozoon is divided into 5 sections
1. Head
2. Neck – where the centriole migrated and connects the head to the tail
3. Midpiece
4. Principal piece
5. Tail or end piece"
Figures and diagrams with these terms will help. Good that a species-specific variation was mentioned:" A capsule composed of dense collagenous material that encloses the testicle is called the tunica albuginea. Most species contain a vascular layer within the tunica albuginea. Horses often contain smooth muscle fibers within the tunica albuginea. The double layer of simple squamous epithelium and mesentery directly covering the testes and apposed to the tunica albuginea is the tunica vaginalis.

Three out of four images in this stack completely lack annotation. None of the images have captions: " FIGURE(S): Rete, Epididymis, Ductus Deferens"

Male Accessory Sex Glands

Here species-specific differences among mammals are noted in the text. Thee would be much more helpful if the differences were illustrated in figures with captions and annotations. Variations in birds and reptiles are not mentioned, which can represent a significant portion of the animals seen in some practices.

This figure complete lacks annotation and captions: " FIGURE(S): Accessory sex glands, Penis"

This section needs diagrams and images: MALE GENITAL LIGAMENTS
MALE EXTERNAL GENITALIA
This section focuses exclusively on mammals. While variation among mammalian penises are described, there is only a single image with no caption or annotation and, with no indication of the species.