ECOLOGY AND BIOLOGY OF THE PACIFIC WALRUS 



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Association C. — Tubule diameter 105-153 /xm; basement membrane 3-5 /^m; 

 epithelium 50-60 fim tall. Spermatogonia mostly like type A; primary and 

 secondary spermatocytes abundant; nuclei of the Sertoli cells mostly indistinct. 

 This is a state of rapid proliferation, before spermiogenesis. 



Association D. — Tubule diameter 128-200 jim; basement membrane 7-8 /xm; 

 epithelium 50-80 /xm tall. Spermatogonia mostly type B; Sertoli cells indistinct; 

 spermatocytes less numerous than in C; round spermatids abundant. 



Association £.— Tubule diameter 156-223 ixm; basement membrane 5 fxm; 

 epithelium 50-80 /xm tall. Spermatogonia mostly type B; Sertoli cells indistinct; 

 spermatocytes and oval to elongate spermatids abundant, the latter occurring in 

 clumps near the margin of the lumen. 



Association F. — Tubule diameter 131-232 fim; basement membrane 2-3 ixm; 

 epithelium 60 jxm tall. Spermatogonia mostly type A. Spermatocytes more 

 abundant than in £; immature (round-oval) spermatids scarce. A few clumps of 

 mature spermatids at the margin of the lumen; spermatozoa abundant in the 

 lumen. A few cell fragments, apparently from degenerating spermatids, also are 

 in the lumen. 



Association G.— Tubule diameter 131-211 /^m; basement membrane 5 /xm; 

 epithelium 50 tall. Spermatogonia mostly type A; Sertoli cells distinct; all 

 ranks of germ cells degenerating and progressing toward the lumen. In the 

 lumen are numerous spermatid giant cells, some with as many as 30 nuclei. 



Association //.— Tubule diameter 115-160 /xm; basement membrane 3 /xm; 

 intact epithelium about 30 fim tall. Spermatogonia mostly type A; Sertoli cells 

 distinct. A few degenerating spermatogonia near the lumen have very large, 

 granular nuclei. The lumen contains a few spermatocyte giant cells and masses of 

 cellular debris. Spermatids are absent. 



In this analysis of the annual histological cycle in the testes, the period of 

 recrudescence is considered to begin with association A and end with C; spermio- 

 genesis extends from D to F, and retrogression from G to H. The complete cycle 

 is continuous; each association grades into the next, and the occurrence of any 

 association never was synchronous in all of the tubules of a testis. 



Each specimen was classified according to the cellular association represented 

 in most of its seminiferous tubules. The results, when ranked by age and month 

 of collection (Table 29), suggest that the timing of onset of spermiogenesis is 

 more erratic in the adolescent and subadult age classes than it is in the adults, 

 and that the period of potency tends to be, usually, 1 to 2 months later in the 

 adolescents and subadults than in the adults. Most mature adults, 15 years old 

 and older, were potent from November to March, whereas the subadults (10-14 

 years) were potent mostly from December or January until May. An age-related 

 difference in seasonal development of the testes was evident also in their weight 

 (Fig. 114) and in the comparative size of their seminiferous tubules. In general, 

 the annual peak of development in tubule size and weight of the testes seemed to 

 occur in February-March in the adolescent and subadult males, and in Decem- 

 ber-January in the adults. 



These findings correspond to those of other investigators. Mansfield (1958a) 

 reported that one adult taken in November and one in March were potent, 

 whereas none of 30 taken in June to October was potent. Gol'tsev (1978) found 

 that, in 115 males taken in March and April, the 8- to 10-year-old animals were 



