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如图,子宫内膜有哪些周期性变化?

 

答案

参考答案:

子宫内膜的周期性变化有两个方面。(1)子宫内膜的组织学变化:子宫内膜在结构上分为基底层和功能层,基底层直接与子宫肌层相连,此层不受月经周期中激素变化的影响,在月经期不发生脱落。功能层靠近宫腔,受卵巢激素的影响产生周期性变化,此层月经期坏死脱落。其组织形态的周期性改变可分为以下3期:①增生期;②分泌期;③月经期。(2)生物化学变化:子宫内膜在雌激素的影响下,间质细胞能产生一种和蛋白质结合的碳水化合物,称酸性粘多糖。雌激素不但能促使酸性粘多糖的产生,还能使之浓缩及聚合,形成基础物质。对增生期子宫内膜起支持作用。排卵后,孕激素阻止酸性粘多糖的合成,使其下降,使间质中的基础物质失去粘稠性,血管通透性增加,内膜可获得充足营养,为受精卵的着床和发育作准备。

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Surprisingly enough, modern historians have rarely interested themselves in the history of the American South in the period before the South began to become self-consciously and distinctively " Southern"—the decades after 1815. Consequently, the cultural history of Britain’s North American empire in the seventeenth and eighteenth centuries has been written almost as if the Southern colonies had never existed. The American culture that emerged during the Colonial and Revolutionary eras has been depicted as having been simply an extension of New England Puritan culture.

However, Professor Davis has recently argued that the South stood apart from the rest of American society during this early period, following its own unique pattern of cultural development. The case for Southern distinctiveness rests_ upon two related premises: first, that the cultural similarities among the five Southern colonies were far more impressive than the differences, and second, that what made those colonies alike also made them different from the other colonies. The first, for which Davis offers an enormous amount of evidence, can be accepted without major recitations, the second is far more problematic.

What makes the second premise problematic is the use of the Puritan colonies as a basis for comparison. Quite properly,Davis decries the excessive influence ascribed by historians to the Puritans in the formation of American culture. Yet Davis inadvertently adds weight to such ascriptions by using the Puritans as the standard against which to assess the achievements and contributions of Southern colonials. Throughout, Davis focuses on the important and undeniable differences between the Southern and Puritan colonies in motives for and patterns of early settlement, in attitudes toward nature and Native Americans, and in the degree of receptivity to metropolitan cultural influences.

However, recent scholarship has ply suggested that those aspects of early New England culture that seem to have been most distinctly Puritan, such as the p religious orientation and the communal impulse, were not even typical of New England as a whole, but were largely confined to the two colonies of Massachusetts and Connecticut. Thus, what in contrast to the Puritan colonies appears to Davis to be peculiarly Southern-acquisitiveness. A p interest in polities and the law, and a tendency to cultivate metropolitan cultural models were not only more typically English than the cultural patterns exhibited by Puritan Massachusetts and Connecticut, but also almost certainly characteristic of most other early modern British colonies from Barbados north to Rhode Island and New Hampshire. Within the larger framework of American colonial life, then, not the Southern but the Puritan colonies appear to have been distinctive, and even they seem to have been rapidly assimilating to the dominant cultural patterns by the last Colonial period.

What is Davis’ attitude toward the Puritans()

A. Davis cries for the excessive influence historians attributed to the Puritans

B. Davis believes in using the Puritans as the standard to evaluate the contributions of Southern colonials

C. Davis concerns more about the differences between the Southern and Northern colonials

D. Davis objects to the difference between the Southern and Puritan colonies