John C. Buckingham

Connective tissue changes incident to cervical effacement

LITTLE inquiry has been directed toward the specific changes which occur in the human cervix to permit effacement and consequent dilatation without injury. It is well known that the nonpregnant cervix is rigid, that it can be dilated only by much force, and that this forcible dilatation may be accompanied by injury or tearing. During pregnancy the cervix becomes softer, but it still cannot be dilated easily except in the event of miscarriage or the onset of labor. In the former case it dilates prior to the passage of any tissue, such that a large Hegar dilator can be introduced with ease; in the latter case it may remain rigid in early labor such that forcible dilatation is impossible. As labor progresses it becomes softer and thinner and dilates without injury to permit the passage of the head. Within a week of delivery, a portion of its old rigidity has returned, and within a month there is little evidence of this dramatic series of events. It is curious that so little effort has been made to explain these Ph enomena.

THE EFFECT OF PREGNANCY AND OF ENOVID ON THE RABBIT VASCULATURE.

T H E observation has been made1 and confirmed29 3 that pregnancy is associated with significant changes in the connective tissue of the human cervix. It has been suggested that probably all connective tissue structures of the body, and not only the cervix, undergo alteration and loss of tensile strength during pregnancy.4 This paper is concerned only with the vasculature, and is a preliminary study designed to determine whether specific gestational changes can be demonstrated by histological techniques. The literature dealing with such changes is not large, but an interesting and suggestive thread runs through it. In his excellent review of the contribution of vascular accidents to maternal mortality, Bryan9 reports between 10 and 20 per cent of all maternal

Connective tissue changes in the cervix during pregnancy and labor.

Research has led experts to the conclusion that the human cervix which becomes softer and increasingly dilatable is basically a connective tissue structure. Such tissue is composed of formed elements and the ground substance both of which are described. The histological changes of the cervix during pregnancy are described and pictured from microscope photography. The ultrastructure of cervical connective tissue is described as are changes in the water hydroxyproline and hexosamine concentrations during pregnancy. The connective tissue action which is responsible for the dilatability of the cervix during pregnancy and delivery is explained. The concentration of water in the cervix increases significantly during pregnancy reaching a peak just before labor. This increase in water does not seem adequate to cause the cervical softening occurring during pregnancy. Relaxin administered during a study produced no histological or chemical changes in the cervix. It is believed that major changes occur in all connective tissue structures during pregnancy. A general study of pregnancy and a particular study of the cervix might increase scientific understanding of both cervical and connective tissue changes in general.

Collagen-muscle ratio in clinically normal and clinically incompetent cervices☆☆☆

Abstract A simple, accurate means of histological quantitation of tissue elements is applied to the study of the human uterine cervix. Employing this device, the amount of muscle was found to be higher in a group of patients with clinical cervical incompetency than in an equivalent area of the cervix in a control group of patients immedaitely following normal labor at term. This finding is regarded as confirmation of the thesis that excessive amounts of muscle may be a factor in the production of cervical incompetency. The several cervices showing no conformity to this thesis strengthen the conviction that cervical incompetency often results from a combination of several factors, rather than from simple trauma, or a deviation in cervical composition.

Regression Rate of Vascular Effects Induced by Pregnancy and by Norethynodrel-Mestranol

Based on results in a previous study showing specific vascular changes as the result of pregnancy and administration of norethynodrel-mestranal in the rabbit an attempt was made to determine how long these changes persist after the conclusion of pregnancy and after withdrawal of norethynodrel-mestranol. 8 pregnant rabbits and 8 norethynodrel-mestranol-treated rabbits were studied. The pregnant rabbits were allowed to deliver at term and 1 was sacrificed every second day from Postpartum Day 1-15. Histological preparations were made. Since normal findings were noted in all cases at 15 days postpartum 3 additional rabbits were sacrificed on different days. In the norethynodrel-mestranol-treated group each animal was treated with .2 mg intramuscularly daily for 6 days and then sacrificed every second day from Day1-15 after conclusion of treatment. 3 additional animals were sacrificed. It was concluded that in the rabbit the vascular effects of pregnancy and of norethynodrel-mestranol disappear at variable rates after the withdrawal of the stimulus. Reticular fragmentation persists until about 15 days after pregnancy conclusion and for 10 days after norethynodrel-mestranol therapy cessation. Acid mucopolysaccharides return to normal immediately in both instances. Muscle changes and elastic tissue changes are virtually normal within 10 days and completely normal within 15 days for both groups.