To recapitulate, the at present accepted theory
concerning the mechanism controlling the menstrual
cycle is, that it is governed by the anterior lobe,
which probably produces two hormones: (1) Prolan A,
which stimulates follicular maturation in the ovary,
and the secretion of oestrone, which in turn causes
the endometrium to develop to the post-menstrual phase,
and. (2) Prolan B, which causes the formation of the
corpus luteum and the secretion of Progesterone, which
advances the development of the endometrium to that of
the pre-menstrual phase.The pituitary then might be termed the conductor
of the instruments of the menstrual orchestra, directing
its harmony, but, from what score must the conductor
beat the tempo? What music is to be played?In plainer terms, is there a higher nervous sexual
centre, which controls the hormone function of the
ipituitary?Hohlweg and Junkmann have suggested by their
experiments on castrated rats, into which implants of
hypophyseal tissue have been made, that the pituitary
is controlled extrinsically by fine nerve connections
to the brain via the pituitary stalk.Theobald has recently put forward an hypothesis from evidence of a clinical nature, which
postulates that there are one or more centres in the
brain, probably in the hypothalmic region, which
regulate the functions of the reproductive tract,
through afferent and efferent neuro-hormonic stimuli.
He considers the efferent route to be composed by:
(1) The hormones of the anterior lobe, and
(2) Nervous impulses to the generative organs;
and the afferent pathway to be composed of:
(1) The hormones of the ovary.
(2) Impulses transmitted from the external
generative organ.
(3) Impulses transmitted from the higher
special centres.This hypothesis is rather novel and attractive,
yet it requires the corroboration of more fundamental
study.It, however, causes a swing of the pendulum in
the opposite direction, in focussing the attention
of investigators of this subject, to a higher centre
or centres, which may be the final link in the chain
whereby the phenomena of menstruation, ovulation,
pregnancy and parturition can be more adequately
explained
