CHAPTER 3 

 ANATOMY 



1. Anatomy, general. 2. Embryology, a) Spermatogenesis. b) Ovulation. 

 c) Earlier stages, d) Later stages. 3. Bones; joints and connective tissues, 

 a) Teeth. 4. Muscles. 5. Vessels and lymphatics, a) Blood. 6. Nervous sys- 

 tem, a) Central 1) Brain. 2} Spinal cord, b) Peripheral. 1) Cerebral. 

 2) Spinal nerves and ganglia. 3) Autonomic. c) Technical methods. 7. Sense 

 organs. 8. Integument. 9. Gastro-pulmonary system, a) Gastro-intestinal 

 system, b) Pulmonary system. 10. Uro-genital system. 11. Endocrine 

 system. 



Since this book purposes to present mainly those results that 

 can be systematically arranged and are in a quantitative form 

 there will appear several divisions of this chapter marked only 

 by references to the literature. 



Further, even in those divisions for which there are some 

 available data it happens in many instances that the presentation 

 of them can be better given in the chapters which treat of growth 

 and in such instances the reader is merely referred to the later 

 place of presentation. These general statements apply to the 

 subsequent chapters as well. 



1. Anatomy, general. In only two instances has the rat been 

 used as the basis for a general presentation of mammalian anat- 

 omy. These are in the books by Martin and Moale, 1884, and 

 Goto, 1906. The remaining references are to studies which ap- 

 ply to portions or systems only (see classified references at the 

 end of the chapter). 



2. Embryology, a) Spermatogenesis. According to Hewer 

 ('14): 



In the newborn animal, active mitosis is occurring in the testis, and 

 at 3J weeks the spermatogonia can be distinguished from the spermato- 

 cytes. No lumen begins to appear in the tubules as a rule until 7 

 weeks. At 8 weeks spermatids are easily distinguishable: at 8| weeks 

 isolated spermatozoa may occasionally be seen. At 9 weeks typical 

 ripe spermatozoa are plentiful, but the fully formed epididymis con- 

 tains no free spermatozoa. At 10 weeks all the tubules show active 



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