<p><span style="font-size: 16px;">The reproductive tissues of male and female humans develop similarly in utero until a low level of the hormone testosterone is released from male gonads. Testosterone causes the undeveloped tissues to differentiate into male sexual organs. When testosterone is absent, the tissues develop into female sexual tissues. Primitive gonads become testes or ovaries. Tissues that produce a penis in males produce a clitoris in females. The tissue that will become the scrotum in a male becomes the labia in a female; that is, they are homologous structures.<br /><span id="fs-idm21052688" style="box-sizing: border-box; display: block; margin: 0px;" data-type="media" data-alt="Micrograph shows human sperm, which have an oval head about 3 microns across and a very long flagellum. Illustration shows that the head is surrounded by the acrosome. The part of the tail closest to the head, called the neck, is thicker than the rest."><img src="http://cnx.org/resources/89866181c872915d19a50809c3bdb2f755735743/Figure_43_03_02ab.jpg" alt="Micrograph shows human sperm, which have an oval head about 3 microns across and a very long flagellum. Illustration shows that the head is surrounded by the acrosome. The part of the tail closest to the head, called the neck, is thicker than the rest." width="575" style="box-sizing: border-box; vertical-align: middle; max-width: 100%; display: block; margin-left: auto; margin-right: auto;" id="" data-media-type="image/jpg" /></span>Human sperm, visualized using scanning electron microscopy, have a flagellum, neck, and head. (credit b: modification of work by Mariana Ruiz Villareal; scale-bar data from Matt Russell)</span></p> <p style="margin: 1em 0px; padding: 0px; outline: 0px; word-wrap: normal; line-height: 16.8px; word-break: normal;"><strong style="margin: 0px; padding: 0px; outline: 0px; word-wrap: normal; word-break: normal;"><span style="margin: 0px; padding: 0px; outline: 0px; word-wrap: normal; word-break: normal; font-size: 16px; line-height: 1.4;">Complete the tasks on the list below:</span></strong></p> <ul style="outline: 0px; word-wrap: normal; word-break: normal; line-height: 16.8px;"> <li style="margin: 0px; outline: 0px; word-wrap: normal; word-break: normal;"><span style="margin: 0px; padding: 0px; outline: 0px; word-wrap: normal; word-break: normal; font-size: 16px; line-height: 1.4;">Read the following page in the OpenStax textbook</span></li> <ul style="outline: 0px; word-wrap: normal; word-break: normal;"> <li style="margin: 0px; outline: 0px; word-wrap: normal; word-break: normal;"><span style="margin: 0px; padding: 0px; outline: 0px; word-wrap: normal; word-break: normal; font-size: 16px;"><a href="http://cnx.org/contents/GFy_h8cu@10.53:B_l5gjDS@3/Human-Reproductive-Anatomy-and">Human Reproductive Anatomy and Gametogenesis</a> </span></li> <ul style="outline: 0px; word-wrap: normal; word-break: normal;"> <li style="margin: 0px; outline: 0px; word-wrap: normal; word-break: normal;"><span style="margin: 0px; padding: 0px; outline: 0px; word-wrap: normal; word-break: normal; font-size: 16px;">Read the entire page</span></li> <ul style="outline: 0px; word-wrap: normal; word-break: normal; line-height: 16.8px;"> <li style="margin: 0px; outline: 0px; word-wrap: normal; word-break: normal;"><span style="margin: 0px; padding: 0px; outline: 0px; word-wrap: normal; word-break: normal; font-size: 16px;">Watch <a href="http://www.dnatube.com/video/2086/Animation-on-Spermatogenesis-by-NurseReview">Animation on Spermatogenesis</a> </span></li> </ul> </ul> </ul> <li style="margin: 0px; outline: 0px; word-wrap: normal; word-break: normal;"><span style="margin: 0px; padding: 0px; outline: 0px; word-wrap: normal; word-break: normal; font-size: 16px;">Use the Glossary at the bottom of the page to help with the vocabulary for this week</span></li> <li style="margin: 0px; outline: 0px; word-wrap: normal; word-break: normal;"><span style="margin: 0px; padding: 0px; outline: 0px; word-wrap: normal; word-break: normal; font-size: 16px;">Use the Review Questions and Free Response questions to check for understanding</span></li> </ul> <p style="margin: 1em 0px 0px; padding: 0px; outline: 0px; word-wrap: normal; line-height: 16.8px; word-break: normal; text-align: right;"><span style="margin: 0px; padding: 0px; outline: 0px; word-wrap: normal; word-break: normal; font-size: 16px;"><span style="margin: 0px; padding: 0px; outline: 0px; word-wrap: normal; word-break: normal; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 14px; line-height: 20px;">Download for free at <a class="sExtlink-processed" style="margin: 0px; padding: 0px; outline-width: 0px; word-wrap: normal; color: #3a549a; word-break: normal;" href="http://cnx.org/contents/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.53">http://cnx.org/contents/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.53</a></span></span></p>