Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 2: Dia-Ins
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit25760/457/
GENERATION. 449 
Some time after sexual union the fluid con¬ 
tained in the vesicles which are about to burst, 
previously transparent and nearly colourless, 
now becomes more viscid and tenacious, some¬ 
what turbid and of a reddish colour ; and in 
some animals it is possible in such ripe vesicles 
to perceive, with the unassisted eye in a favour¬ 
able light, a whitish opaque spot on the most 
prominent part, indicating the layer of granules 
or proligerous disc, in the centre of which the 
ovum is situated. After a certain time a small 
opening is formed at the most prominent part 
of the coverings of the vesicle, the vesicle bursts, 
and its contents escape through the opening ; 
they are received in the infundibulum, which is 
now applied firmly against the ovary ; and the 
ovum entering the Fallopian tube is conveyed 
along it, probably by its slow and gradual ver¬ 
micular contractions, until it at last arrives in 
the uterus. 
With regard to the time at which the opening 
of the ovarian vesicles takes place, there are 
considerable varieties in the same and in diffe¬ 
rent animals. In the sheep, the vesicle has 
been found burst so early as at two hours after 
coition. In the dog, Haller found the vesicles 
burst before the sixth day ; in one instance the 
day after coition ; but Prévost and Dumas, not 
until the seventh or eighth. In the rabbit, 
Cruikshank observed vesicles burst two hours 
after coition, while Haighton considers forty- 
eight hours as the usual time at which the rup¬ 
ture happens in this animal. M. Coste has 
observed it most frequently between the second 
and third day in the rabbit. 
After the bursting of the Graafian vesicles, 
there occur in them and in the neighbouring 
part of the ovary some important changes of 
structure, which claim our attention in this 
place as intimately connected with that part of 
the process of conception which is now under 
consideration. 
If the Graafian vesicle which is enlarged 
from venereal excitement and is ready to burst, 
be examined with care, it will be seen that at 
the most prominent part of its coats the blood¬ 
vessels converge towards the point at which 
rupeds, (Annal, d. Seien. Nat. tom. iii. p. 135,) 
but without any certainty or exact knowledge as to 
their nature. M. Coste, with a spirit of appropria¬ 
tion too common, we regret to say, among his coun¬ 
trymen, has taken advantage of some speculative 
views and strained analogies brought forward by 
Baer concerning the bodies which he discovered, in 
which he compared them (erroneously as we think) 
to the germinal part only of the ovum, rather than 
to the whole ovum of the oviparous animal, to take 
from the merits of Baer in their discovery ; but we 
feel assured that every unprejudiced inquirer who 
reads with attention Baer’s admirable “ Epistola 
de Ovi Mammalium et Hominis Genesi,” in which 
his discovery was first announced in 1827, and 
compares it with other works on the subject, 
will be convinced that Baer has no sharer in the 
discovery, and fully understood the nature of the 
ovarian ovum of viviparous animals ; although 
it may be the case that subsequent investigations 
have added considerably to the knowledge of the 
relations of these ova. We shall return to a more 
minute detail of this body in considering the process 
of formation of the ovum in the present article and 
under the article OVUM. 
the rupture afterwards takes place, and this 
point is itself comparatively destitute of blood¬ 
vessels.* 
At the time of the formation of the opening 
into the vesicle, from the division of some of 
the bloodvessels, a small quantity of blood is 
generally mixed with the fluid contents of the 
vesicle ; and after the vesicle has been emptied 
of these fluid contents, their place is generally 
supplied by a greater or less quantity of coagu¬ 
lated blood, probably poured out by the same 
ruptured vessels. 
The membranes of the vesicle at this time 
have become thicker than before: the inner 
one in particular appears more vascular and 
uneven, perhaps in part from its being puckered 
up on the vesicle becoming flaccid and com¬ 
paratively empty. The wrinkled appearance 
on the inner surface of the vesicle increases, 
and there grows gradually out from it a new 
substance which comes to occupy the whole 
cavity of the vesicle ; and in many instances, 
as this new substance is formed in greater 
quantity than can be contained within the limits 
of the vesicle, it protrudes some way out at 
the opening of the vesicle, forming a dark red 
prominence like a nipple, which rises above 
the neighbouring surface of the ovary. This 
substance, at the time of its first formation, is 
of a pink or reddish colour, but as it becomes 
gradually less filled with blood it acquires a 
yellowish hue, which is more or less apparent 
in different animals. In the human species it 
is of a bright yellow colour, whence the name 
of corpus luteum applied to this new produc¬ 
tion of the ovarian vesicles. 
The substance of the corpus luteum has a 
lobular structure; the lobules radiating in a 
somewhat irregular manner from the centre to 
the circumference. The central part of the 
corpus luteum frequently remains hollow for 
some time after its production, opening ex¬ 
teriorly by a narrow passage from the place 
where the rupture of the vesicle originally took 
place ; at other times this passage is closed 
more early, and there remains nothing but an 
indication of its place in a depression in the 
centre of the most projecting part of the corpus 
luteum. The lobules of the corpus luteum, 
examined with the microscope, exhibit merely 
a granular structure, and are not formed of 
acini, as some have described them, so that 
there is no reason to consider these bodies as 
of a glandular nature. 
The size which corpora lutea attain when 
fully developed varies much in the same and 
in different animals. In the human female 
they become as large as a common hazel-nut ; in 
the cow they are sometimes as large as a ches- 
* The ovarian capsules of the bird, which are 
obviously the analogous parts of the ovarian 
vesicles of quadrupeds, present on their most pro¬ 
minent part a remarkable band, extending for 
nearly one-third of the periphery : towards the 
margins of this band the small bloodvessels all 
converge, but they do not pass upon the band 
itself, so that it is left free from bloodvessels. It 
is in this non-vascular or less vascular part of the 
capsule that the rupture takes place when the yolk 
escapes.
        

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