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Roentgen cephalometric studies on skull development in rats. II. Normal and hypophysectomized males; sex differences
Author(s) -
Wright Howard V.,
Kjaer Inger,
Asling C. Willet
Publication year - 1966
Publication title -
american journal of physical anthropology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.146
H-Index - 119
eISSN - 1096-8644
pISSN - 0002-9483
DOI - 10.1002/ajpa.1330250202
Subject(s) - neurocranium , skull , roentgen , hypophysectomy , synchondrosis , cephalometry , facial skeleton , anatomy , biology , medicine , endocrinology , orthodontics , nuclear medicine , hormone
Growth of the skull in normal male rats of the Long‐Evans strain has been studied by serial roentgen cephalometry (under anesthesia) from 27 to 280 days of age, and has been compared with the retardation following hypophysectomy and with growth data obtained on females in an earlier similar study. The dimensions measured represented major skull regions and segments, and in some instances allowed calculation of indices (e.g., neurocranial width/length ratio) which would show changing proportions. In general, the skull showed the more rapid and prolonged growth characteristic of male rats' skeletal development when compared with that of females. Viscerocranial (“facial”) length and width were notable in this respect. On the other hand, growth in neurocranial width and height ceased at a time and size much like that in females. Examination of the possibility that the adult female skull might correspond closely to that of an immature male disclosed that though this might be true for the neurocranium, facial dimensions showed distinctive sex differences. After hypophysectomy at 27 days of age males (as also females) showed marked reduction of growth but not complete cessation. Dimensional increases were between one‐fifth and one‐fourth of the normal gains. The ratios computed showed that the proportions of infancy were retained after early hypophysectomy.