. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 4io DISCOVERY REPORTS Lactating females with one corpus albicans in the ovaries will be in their first lactation and in the material there are seven such records. The criterion of full lactation which is adopted here is discussed below (p. 444). During the first lactation the gland undergoes an apparently irreversible change; it may enlarge to over 20 cm. in thickness (mean 16-1 cm., range 8-24 cm.) and although it involutes after weaning (or death) of the calf it does not revert to the former i
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 4io DISCOVERY REPORTS Lactating females with one corpus albicans in the ovaries will be in their first lactation and in the material there are seven such records. The criterion of full lactation which is adopted here is discussed below (p. 444). During the first lactation the gland undergoes an apparently irreversible change; it may enlarge to over 20 cm. in thickness (mean 16-1 cm., range 8-24 cm.) and although it involutes after weaning (or death) of the calf it does not revert to the former immature condition. In females which have previously experienced at least one lactation period the mammary glands are either immediately post-lactation in condition or what Mackintosh and Wheeler (1929) termed 'resting' or 'intermediate' between this condition and lactation (see below, p. 444). The mammary glands are then usually more than 3 cm. deep (from 2-5 to 14 cm., Text-fig. 35) and there are brown lobes of coiled ducts set in a thick connective tissue framework (Mackintosh and Wheeler, 1929, 25 - 15 X 10. 10 20 o 10 so o 10 PUBERTY PREGNANCY LACTATION PRIMIPAROUS SECOND FULL PREGNANCY LACTATION END OF LACTATION MULTIPAROUS - Text-fig. 35. Frequency distribution of mammary gland depth in several groups of female fin whales. fig. 138; van Lennep and van Utrecht, 1953, fig. 1). Apart from the usually greater thickness, the colour and appearance of ' resting' or ' intermediate' mammary glands is quite different from that of the gland which has not yet been functional. The gross appearance of the mammary gland in section is, therefore, considered to be a reliable criterion of nulliparous or primiparous females. The first pregnancy There are 88 pregnant fin whale females in the material which can be classed as primiparous on the grounds outlined above. This figure includes only those individuals for which data on both mammary development and ovaries are available; it excludes f
Size: 1930px × 1294px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
