Chapter 34, Problem 1RQ

Outline Berthold’s first endocrine experiment. What was the hypothesis?

Summary Introduction

To outline: The first endocrine experiment conducted by Berthold’s and to explain its hypothesis.

Introduction: Endocrinology is a branch of biology and medicine that deals with the endocrine system of a body. The endocrine system has glands that secrete chemical messengers known as hormones. The hormones control several organs and organ systems of the body. Examples of hormones include insulin, growth hormone, and thyroid hormone.

Explanation of Solution

The first endocrinology experiment was conducted by Professor Arnold Adolph Berthold in the year 1849.

The outline of the endocrine experiment is as follows:

Hypothesis: To understand if the blood-borne chemical signal produced by the testes influences both the physical and behavioral characteristics in an adult chicken.

Method:  Berthold chose castrated male chickens for the experiment. It was divided into three groups:

Group 1 - Castrated male chickens without any treatments. 

Group 2 -  Castrated male chickens with their own testes reimplanted. 

Group 3 - Castrated male chickens with testes implanted from different chicken.  Berthold killed and dissected the chickens after they were matured. The testes from the chickens were also examined.

Results:  The observations of Berthold from the experiment were, in Group 1, the chickens grew and developed into capons, with no interest in hens. These chicks lacked aggressive behavior and rooster feathers.  Group 2 and 3 chickens behaved and looked the same.  Both groups developed male aggressive behavior and rooster plumage.  The transplanted testes examined from Group 3 chickens showed that they developed their own blood supply and produced normal functions.

Conclusion:  The development of male characteristics in a chicken both physical and behavioral was through a chemical signal carried in the blood and that no nerve supply was essential.