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Contrasting mechanisms of penile urethral formation in mouse and human.
This paper addresses the developmental mechanisms of formation of the mouse and human penile urethra and the possibility that two disparate mechanisms are at play. It has been suggested that the entire penile urethra of the mouse forms via direct canalization of the endodermal urethral plate. While this mechanism surely accounts for development of the proximal portion of the mouse penile urethra, we suggest that the distal portion of the mouse penile urethra forms via a series of epithelial fusion events. Through review of the recent literature in combination with new data, it is unlikely that the entire mouse urethra is formed from the endodermal urethral plate due in part to the fact that from E14 onward the urethral plate is not present in the distal aspect of the genital tubercle. Formation of the distal portion of the mouse urethra receives substantial contribution from the preputial swellings that form the preputial-urethral groove and subsequently the preputial-urethral canal, the later of which is subdivided by a fusion event to form the distal portion of the mouse penile urethra. Examination of human penile development also reveals comparable dual morphogenetic mechanisms. However, in the case of human, direct canalization of the urethral plate occurs in the glans, while fusion events are involved in formation of the urethra within the penile shaft, a pattern exactly opposite to that of the mouse. The highest incidence of hypospadias in humans occurs at the junction of these two different developmental mechanisms. The relevance of the mouse as a model of human hypospadias is discussed
Agricultural wage labour in fifteenth-century England
This dissertation is researching the employment of different types of agricultural labourer in the ending phase of the middle ages. The purpose is to question the method of using casual wage evidence to interpret changes in the labourerâs income in the current study of late medieval economic history. My criticism of the traditional method is that, since casual wage evidence is composed of the price of finishing a piece of work, it is inappropriate to use that evidence to interpret incomes without the information of how many pieces of work done by the labourer. The said information is, indeed, mostly unavailable. My proposition to solve this problem is to use the salaries paid to the permanent farm worker, who was hired by year. The approach of this research is, firstly, to demonstrate the limitations of the traditional method and, secondly, to demonstrate that the salary paid to the permanent worker is a useful tool for understanding the changes in the labourerâs income. In particular, the discussion is separated into five chapters. At first, I intend to illustrate that casual wage evidence illustrates only one aspect of the fifteenth-century agricultural labour market and that from the same source material more information apart from wage data is available and allows us to examine other aspects of wage labour. With the information, I shall argue that job opportunities in the casual sector were limited by farming seasons; and that, except for a few villagers, casual employment only accounted for a minor part of the yearly income. It shall be illustrated that apart from casual labourers, the manorial demesne employed the other two types of labourers, who were potentially more important than casual labourers in terms of the cost and the labour input. Between the two, labour services were persistently employed, but their important were dwindling, whilst the permanent workers were the main labour force purposely maintained on the demesne. This finding proves that the employment of casual labour was relatively insignificant. It also illustrates that the permanent posts were a more secure source of income than casual hire. In this context, casual hire was paid higher daily wages, but its availability was limited; the permanent contract was poorly paid, but it guaranteed a secure livelihood across the year. This explains why, when job opportunities were relatively expanded in the casual sector during labour shortage, labourers would turn down permanent contracts for casual hire, in the hope for a better income. Following this context, we would expect to see that during our period, when depopulation was continued, the employer of permanent workers was forced to improve the job offer to match the potential income a labourer could earn in the casual sector. The trend in the value of the permanent labourerâs salary, therefore, should reflect the changes in the agricultural labourerâs income in general. An index of the permanent labourerâs salary will be presented to illustrate this rising trend
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Clitoral development in the mouse and human.
The goal of this report is (a) to provide the first detailed description of mouse clitoral development, and (b) to compare mouse and human clitoral development. For this purpose, external genitalia of female mice were examined by wholemount microscopy, histology and immunohistochemistry from 14 days of gestation to 10 days postnatal. Human clitoral development was examined by these techniques as well as by scanning electron microscopy and optical projection tomography from 8 to 19 weeks of gestation. The adult mouse clitoris is an internal organ defined by a U-shaped clitoral lamina whose development is associated with the prenatal medial and distal growth of the female preputial swellings along the sides of the genital tubercle to form the circumferential preputial lamina. Regression of the ventral aspect of the preputial lamina leads to formation of the U-shaped clitoral lamina recognized as early as 17 days of gestation. While the adult U-shaped mouse clitoral lamina is closely associated with the vagina, and it appears to be completely non-responsive to estrogen as opposed to the highly estrogen-responsive vaginal epithelium. The prominent perineal appendage in adult females is prepuce, formed via fusion of the embryonic preputial swellings and is not the clitoris. The human clitoris is in many respects a smaller anatomic version of the human penis having all of the external and internal elements except the urethra. The human clitoris (like the human penis) is derived from the genital tubercle with the clitoral glans projecting into the vaginal vestibule. Adult morphology and developmental processes are virtually non-comparable in the mouse and human clitoris
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