What is the Difference Between Megasporophyll and Microsporophyll

The main difference between megasporophyll and microsporophyll is that megasporophyll bears megasporangia, which produce megaspores, whereas microsporophyll bears microsporangia, which produces microspores. Furthermore, spores produced by the megasporophyll develop into the female gametophyte, while the spores produced by the microsporophyll develop into the male gametophyte.  

Megasporophyll and microsporophyll are the two types of sporophylls or the leaves which bear sporangia. Conifers, ferns, lycophytes, and brown algae produce sporophylls. 

Key Areas Covered 

1. What is Megasporophyll
     – Definition, Structure, Function
2. What is a Microsporophyll
     – Definition, Structure, Function
3. What are the Similarities Between Megasporophyll and Microsporophyll
     – Outline of Common Features
4. What is the Difference Between Megasporophyll and Microsporophyll
     – Comparison of Key Differences

Key Terms 

Female Gametophyte, Male Gametophyte, Megasporophyll, Microsporophyll, Sporophylls

What is Megasporophyll 

Megasporophyll is a type of leaf-like structure produced by heterosporous plants such as seed plants, lycophytes, and some ferns. Generally, it produces megasporangia, sacs that produce megaspores of female spores. Moreover, in seed plants, ovule serves as the megasporangium. Ovules occur inside the ovary in angiosperms and inside the female cone in gymnosperms.

Figure 1: Cycas platyphylla Female Cone

Furthermore, the integuments, nucellus, and embryo sac are the three structural parts of the ovule. Here, integuments are the outer layers of the ovule, while nucellus is the inner mass. The megaspore cell serves as the embryo sac, developing into the female gametophyte. 

What is a Microsporophyll 

Microsporophyll is the other type of leaf-like structure produced by the heterosporous plants. In contrast, it produces microsporangia, the sacs which produce microspores or the male spores. Generally, in some plants such as cycads, ferns, and lycophytes, sporophylls aggregate into strobili, which are distributed singly among sterile leaves.

Figure 2: Cycas platyphylla Male Cone 

Both microsporophylls and megasporophylls can be intermixed or separately occur in different patterns. Also, their sporangia occur either in the axil or on the adaxial surface of the sporophyll.  

Similarities Between Megasporophyll and Microsporophyll

• Megasporophyll and microsporophyll are the two types of sporophylls that contain sporangia. 
• Generally, sporangia produce spores, which germinate and develop into gametophytes. 
• Moreover, gametophytes produce gametes, which ultimately undergo fertilization. 
• Therefore, both megasporophyll and microsporophyll are two types of reproductive structures of heterosporous plants such as conifers, ferns, lycophytes, and brown algae. 
• Usually, they are leaf-like structures with bulb-like heads, which produce spores.  

Difference Between Megasporophyll and Microsporophyll 

Definition 

Megasporophyll refers to the sporophylls which bear megasporangia while microsporophyll refers to the sporophylls which bear microsporangia. Thus, this is the main difference between megasporophyll and microsporophyll

In Angiosperms 

Moreover, megasporophyll is rolled to produce a carpel in angiosperms while microsporophyll is modified into stamens. 

Produces 

The major difference between megasporophyll and microsporophyll is that megasporophylls produce megaspores while microsporophylls produce microspores. 

Shedding of Spores 

Besides, while megasporophyll does not shed its spores, microsporophyll sheds its spores.  

Gametophytes 

Also, the spores produced by the megasporophyll develop into female gametophytes while the spores produced by microsporophyll develop into male gametophytes. Hence, this is also an important difference between megasporophyll and microsporophyll.

Gametophyte Formation 

Additionally, the female gametophyte is formed inside the megasporangium in seed plants, while the male gametophyte is formed near the female gametophyte.  

Gametes 

Furthermore, megasporophylls are responsible for the production of female gametes, while the microsporophylls are responsible for the production of male gametes. 

Conclusion 

Megasporophyll is a leaf-like structure of plants. Significantly, it bears megasporangia, which produce megaspores or female spores. Further, megaspores develop into the female gametophyte. However, as megaspores are not shed, the development of the female gametophyte occurs inside the megasporangium. Ultimately, the female gametophyte produces female gametes. On the other hand, microsporophyll is the second leaf-like structure which bears microsporangia. Microsporangia produce microspores, which develop into male gametophytes near the female gametophyte. Therefore, microspores are shed from the microsporophyll to reach the megasporophyll. Moreover, the male gametophyte produces male gametes. Hence, the main difference between megasporophyll and microsporophyll is the type of sporangia found on them. 

References:

1. “Sporophyll.” Wikipedia, Wikimedia Foundation, 24 May 2019, Available Here.

Image Courtesy:

1. “Cycas platyphylla Female cone” By tanetahi from far-north Queensland, Australia – Cycas platyphyllaUploaded by berichard (CC BY 2.0) via Commons Wikimedia 
2. “Cycas platyphylla Male cone 2” By tanetahi from far-north Queensland, Australia – Cycas platyphyllaUploaded by berichard (CC BY 2.0) via Commons Wikimedia