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Updated: May 25, 2025
Again it is difficult, it might be said impossible, to believe that an accidental mutation gave rise to corpora lutea the secretion of which caused uterine gestation and ultimately the formation of the placenta.
The evolutionist, on the other hand, asks what was the origin of this corpora lutea, why should the ruptured ovarian follicles after the escape of the ova in Mammals undergo a progressive development and persist during the greater part of the whole of pregnancy?
It is also, in my opinion, unreasonable to suppose that the rudimentary corpora lutea of lower viviparous Vertebrates arose as a mutation the result of which was to cause internal development of the ovum.
Before considering further the question of the corpora lutea as organs of internal secretion, we may briefly refer to the origin and structure of these bodies and of other parts of the mammalian ovary.
As Sandes says the 'greater part of the period of lactation, it would appear that absorption of the corpora lutea takes place when the young Dasyurus have grown to some size, become covered with hair, and are able to leave the teats or even the pouch at will.
In the specimens of Dasyurus described by O'Donoghue, in which the milk glands developed after ovulation without ensuing pregnancy, normally developed corpora lutea were present in the ovary.
Under these conditions it is obvious that diffusion of chemical substances from the young through the walls of the pouch would come to an end. It would be interesting in this connexion to know more of the relation of egg and embryo to the pouch and to the corpora lutea in Echidna. In Ornithorhynchus the eggs are hatched in a nest and there is no pouch.
The true corpora lutea arise from follicles in which the ova have become mature and from which they have escaped through the surface of the ovary. Buds from the theca interna invade the follicle and form the connective tissue of the corpus luteum.
The river, a dark, sluggish stream, about fifty feet wide, the channel by which the Mud Lakes and Little Tupper's Lake, with its connected lakes and ponds, empty into Tupper's Lake, is a favorite feeding-ground with the deer, whose breakfast is made on the leaves of the Nuphar lutea which edge the stream.
On this view that the corpora lutea are the result, not the cause, of intra-uterine gestation, it would no longer be possible to maintain the theory that the corpus luteum in the human species is the cause by its internal secretion of the phenomenon of menstruation. Leopold and Ravana found that ovulation as a rule coincides with menstruation, but may take place at any time.
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