. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 396 DISCOVERY REPORTS whales under 3 hr. post-mortem are rare on factory ships or land stations. The insulating layer of blubber probably accelerates post-mortem changes. Chittleborough has studied the histology of humpback-whale testes from animals in breeding condition, but the material shows signs of post- mortem degenerative changes, with the result that even his material does not present a clear picture of full spermatogenesis (Chittleborough, 19556, PI. 1, fig. 4). In most cases it has bee
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 396 DISCOVERY REPORTS whales under 3 hr. post-mortem are rare on factory ships or land stations. The insulating layer of blubber probably accelerates post-mortem changes. Chittleborough has studied the histology of humpback-whale testes from animals in breeding condition, but the material shows signs of post- mortem degenerative changes, with the result that even his material does not present a clear picture of full spermatogenesis (Chittleborough, 19556, PI. 1, fig. 4). In most cases it has been found possible to diagnose a male in full breeding condition or in complete anoestrus, but it is not possible to describe the more gradual histological changes accompanying the approach to or regression from full breeding activity as was possible with well-fixed material collected from seals immediately after death (Laws, 1956c). A preliminary examination is sufficient to show that most male fin whales examined in the. MONTHS 250 200 5 < 150 IOO S AFRICA ANTARCTIC V J A S MONTHS Text-fig. 28. Annual cycle of testis activity in the male. Above, activity expressed as arbitrary scale of values, based on histological appearance; below, measurements of mean diameters of seminiferous tubules; from Antarctic and South Africa. Antarctic are in full anoestrus, but there are some individuals in which the seminiferous tubules present a more active picture. Since detailed histological examination and description is not rewarding, a subjective classification into five arbitrary stages of activity has been made using the sectioned material on which Mackintosh and Wheeler (1929) based their account of the male cycle. This includes 86 specimens, mostly from January and February, but including all months except June. On the basis of the overall microscopic appearance the material has been divided into five classes—o, 1, 2, 3 and 4, ranging from complete anoestrus to full activity. The mo
Size: 2336px × 1069px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
