Embryology - 23 Apr 2024 Expand to Translate
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Nelsen OE. Comparative embryology of the vertebrates (1953) Mcgraw-Hill Book Company, New York.

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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding. (More? Embryology History \| Historic Embryology Papers)

Part I The Period of Preparation

Part I - The Period of Preparation: 1. The Testis and Its Relation to Reproduction | 2. The Vertebrate Ovary and Its Relation to Reproduction | 3. The Development of the Gametes or Sex Cells

The events which precede the initiation of the new individual's development are:

The preparation of the male and female parents and their reproductive structures for the act of reprcxluction (Chaps. 1 and 2).
The preparation of the gametes (Chap. 3).

The anterior lobe of the pituitary gland, because of its secretion of the gonadotrophic (gonad-stimulating) hormones, is the pivotal structure in the reproductive mechanism.

The gonadotrophic hormones are:

Follicle-stimulating hormone, FSH;
Luteinizing hormone, LH (ICSH), and
Luteotrophin, LTH.

The Testis and Its Relation to Reproduction

1. The Testis and Its Relation to Reproduction

A. Introduction

General description of the male reproductive system
Importance of the testis

B. Anatomical features of the male reproductive system

Anatomical location of the testis
Possible factors involved in testis descent
General structure of the scrotum and the testis in mammals a. Structure of the scrotum b. General structure of the testis
Specific structures of the mammalian testis which produce the reproductive cells and the male sex hormone a. Seminiferous tubules b. Interstitial tissue
The testis of vertebrates in general
Accessory reproductive structures of the male a. The reproductive duct in forms utilizing external fertilization b. The reproductive duct in species practicing internal fertilization c. Specific activities of the various parts of the male reproductive system

The Vertetrate Ovary and Its Relationship to Reproduction

2. The Vertebrate Ovary and Its Relation to Reproduction

A. The ovary and its importance

B. Preformationism, past and present

C. General structure of the reproductive system of the vertebrate female

1. General structure of the ovary

2. General structure of the accessory reproductive organs

D. Dependency of the female reproductive system on general body conditions

1. Inanition

2. Vitamins

a. Vitamin A

b. Vitamin B

c. Vitamin C

d. Vitamin E

3. The hypophysis (pituitary gland)

E. Activities of the ovary in producing the reproductive state

1. The ovary as a â€œstorehouseâ€ of oogonia

2. Position occupied by the primitive female germ cells in the ovarian cortex

3. Primary, secondary, and tertiary follicles of de Graaf

4. Hormonal factors concerned with the development of egg follicles

a. Effects produced by the gonadotrophic hormones of the development of the mammalian egg follicle

b. Stimulating effects of the gonadotrophins on the ovaries of other vertebrates

5. Structure of the vertebrate, mature egg follicle

a. Structure of the mature follicle in metatherian and eutherian mammals

b. Structure of the prototherian egg follicle

c. Egg follicles of other vertebrates

6. Ovulatory process; possible factors controlling ovulation

a. Process of ovulation in higher mammals

1) Changing tissue conditions culminating in egg discharge from the ovary

2) Hormonal control of the ovulatory process

b. Ovulation in vertebrate groups other than the higher mammals

1) Hen

2) Frog

3) Hormonal control of ovulation in lower vertebrates

c. Comparison of the immediate factors affecting egg discharge in the vertebrate group

7. Internal conditions of the ovary as an ovulatory factor

8. Number of eggs produced by different vertebrate ovaries

9. Spontaneous and dependent ovulation in the mammals and in other vertebrates

10. Egg viability after discharge from the ovary

11. History of the egg follicle after ovulation

a. Follicles which do not develop a post-ovulatory body

b. Follicles which develop a post-ovulatory body; formation of the corpus luteum

12. Hormones of the ovary and their activities in effecting the reproductive condition

a. Estrogenic hormone

1) Definition and source of production

2) The ovary as the normal source of estrogen in the non-pregnant female

3) Pituitary control of estrogen formation

4) Effect of estrogen upon the female mammal

5) Effects of estrogen in other vertebrates

b. Progesterone â€” the hormone of the corpus luteum

1) Production of progesterone

2) Effects of progesterone

F. Reproductive state and its relation to the reproductive cycles in female vertebrates

1. Sexual cycle in the female mammal

a. Characteristics and phases of the reproductive cycle

b. Relation of cstrus and ovulation in some common mammals

1) Spontaneously ovulating forms (Sexual receptivity of male occurs at or near time of ovulation)

2) Dependent ovulatory forms (Sexual receptivity [heat] occurs previous to time of ovulation)

c. Non-ovulatory (anovulatory) sexual cycles

d. Control of the estrous cycle in the female mammal

e. Reproductive cycle in lower vertebrate females

G. Role of the ovary in gestation (pregnancy)

1. Control of implantation and the maintenance of pregnancy in mammals

2. Gestation periods, in days, of some common mammals

3. Maintenance of pregnancy in reptiles and other vertebrates

H. Role of the ovary in parturition or birth of the young

I. Importance of the ovary in mammary-gland development and lactation

J. Other possible developmental functions produced by the ovary

K. Determinative tests for pregnancy

The Development of the Gametes or Sex Cells

3. The Development of the Gametes or Sex Cells

A. General considerations

B. Controversy regarding germ-cell origin

C. Maturation (differentiation) of the gametes

1. General considerations

2. Basic structure of the definitive sex cell as it starts to mature or differentiate into the male meiocyte (i.e., the spermatocyte) or the female meiocyte (i.e., the oocyte)

3. Nuclear maturation of the gametes

a. General description of chromatin behavior during somatic and meiotic mitoses

b. Reductional and equational meiotic divisions and the phenomenon of crossing over

c. Stages of chromatin behavior during the meiotic prophase in greater detail

1) Leptotene (leptonema) stage

2) Zygotene or synaptene (zygonema) stage

3) Pachytene (pachynema) stage

4) Diplotene (diplonema) stage

5) Diakinesis

d. Peculiarities of nuclear behavior in the oocyte during meiosis; the germinal vesicle

e. Character of the meiotic (maturation) divisions in the spermatocyte compared with those of the oocyte

1) Dependent nature of the maturation divisions in the female meiocyte

2) Inequality of cytoplasmic division in the oocyte

f. Resume of the significance of the meiotic phenomena

4. Cytosomal (Cytoplasmic) maturation of the gametes

a. General aspects of the cytoplasmic maturation of the gametes

b. Morphogenesis (spermiogenesis) ( sperm ioteleosis) of the sperm

1) Types of sperm

2) Structure of a flagellate sperm

a) Head

b) Neck

c) Connecting body or middle piece

d) Flagellum

3) Spermiogenesis or the differentiation of the spermatid into the morphologically differentiated sperm

a) Golgi substance and acroblast; formation of the acrosome

b) Formation of the post-nuclear cap

c) Formation of the proximal and distal centrioles; axial filament

d) Mitochondrial material and formation of the middle piece of the sperm

e) The cytoplasm, axial filament, mitochondria, and tail formation

c. Cytoplasmic differentiation of the egg

1) Types of chordate eggs

a) Homolecithal (isolecithal) eggs

b) Telolecithal eggs

2) Formation of the deutoplasm

3) Invisible morphogenetic organization within the cytoplasm of the egg

4) Polarity of the egg and its relation to body organization and bilateral symmetry of the mature egg

5) Membranes developed in relation to the oocyte; their possible sources of origin

a) Chorion in St ye la

b) Egg membranes of Amphioxus

c) Vitelline membrane and zona radiata of elasmobranch fishes

d) Zona radiata of teleost fishes

e) Vitelline membrane (zona radiata) in amphibia

f) Zona radiata (zona pellucida) of the reptile oocyte

g) Vitelline membrane (zona radiata) of the henâ€™s egg

h) Membranes of the mammalian oocyte

5. Physiological maturation of the gametes

a. Physiological differentiation of the sperm

b. Physiological ripening of the female gamete

D. Summary of egg and sperm development

Part I - The Period of Preparation: 1. The Testis and Its Relation to Reproduction | 2. The Vertebrate Ovary and Its Relation to Reproduction | 3. The Development of the Gametes or Sex Cells

Cite this page: Hill, M.A. (2024, April 23) Embryology Book - Comparative Embryology of the Vertebrates 1. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_Comparative_Embryology_of_the_Vertebrates_1

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